The present invention relates in general to sewing machines and in particular to a new and useful embroidering machine wherein groups of threaded needles are utilized, one at a time, to produce embroidery.
To obtain an embroidery having a neat appearance, it is desirable to conceal the ends of both the locking threads and the needle threads on the underside of the embroidered work. To this end, the embroidering threads are cut in such a way that the cut needle-thread ends carried by the needles are sufficiently, but not too long, so that during the formation of the initial stitch of a stitch group including several stitches, the needle threads securely interlock with the locking threads and the ends of the needle threads are completely pulled through the work to the underside thereof. In embroidering machines having embroidering heads equipped with a plurality of needles assembled into a group and where each needle is threaded with a thread of its own and only one needle can be brought into the working position at a time, it is further required to keep the thread ends carried by needles in a rest position, away from the working area, to avoid their inadvertent being picked up during the operation.
In another prior art embroidering machine (Swiss Pat. No. 65,330), the presser feet are designed as thread clamps. After making an embroidery stitch group, the embroidering frame carrying the work is displaced until the needle threads extending from the needle to the work come to lie in front of a receiving slot of the presser feet. Then, by means of an elongated slide moved along the presser feet, the needle threads are pushed, one after the other, into the clamps of the presser feet and immediately cut. Since in this embroidering machine all the needles are moved simultaneously, the device is not suitable for embroidering machines having embroidering head with a group of individually operable needles. Further, since the pressure feet are provided at locations which are laterally spaced from the respective needles, they cannot satisfactorily keep the work down in the close proximity of the needles, so that at the withdrawal of the needles from the work, the work may partly be taken along and thus flutter. Another disadvantage is that due to the use of an elongated slide traveling along the presser feet, the embroidering machine requires much space.
Still another prior art embroidering machine (U.S. Pat. No. 3,349,733) comprises a plurality of needles, drivable by groups, and an equal number of clamping or holding devices for the needle threads, which are provided laterally of the needles and closely spaced from the work. With the last stitch of a stitch group done, the frame carrying the work is displaced through a relatively long distance, whereby the needle thread portions extending from the needles to the work are brought into the proximity of the clamping devices. At the same time, further thread lengths are pulled off the supply bobbins. To bring the needle threads into the open clamping jaws of the clamping devices, all clamping devices are moved in the direction of the needle threads and then closed. Upon cutting the threads, the needle-thread ends carried by needles which will not be used in the next embroidering operation are retained in the respective clamping devices, while the other needle-thread ends are released prior to the start of the initial stitch.
Since the clamping devices are closely spaced from the work, there is a risk, even with a work stretched in a vertical plane and horizontally reciprocating needles, that the needle-thread ends hanging from the closed clamping devices will be picked up during the embroidering operation by the adjacent, driven needles and worked into the embroidery. Clamping devices in such arrangement are therefore, unsuitable for embroidering machines in which the work extends horizontally and the needles are moved vertically. Another disadvantage is that after the last stitch in a stitch group, the frame carrying the work must be displaced through a relatively large distance, to get the needle thread to the clamping devices. If, for example, after a change to another color of the needle threads, the next stitch is to be made in close proximity of the last stitch, the frame or work must first be returned into its initial position.